Transformations of the honeycomb-moths.
a a a, Galleries of the cell-boring caterpillar; b, the female;
c, the male moth (Galleria alvearia);
d d d d, galleries of the wax-eating caterpillar,
e, seen at the entrance; f, the same exposed;
g, its cocoon; h, the moth (Galleria cereana).
When the structure is finished, the insect deems itself secure to feed on the materials of the cloth or other animal matter within its reach, provided it is dry and free from fat or grease, which Réaumur found it would not touch. This may probably be the origin of the practice of putting a bit of candle with furs, &c., to preserve them from the moth. For building, it always selects the straightest and loosest pieces of wool, but for food it prefers the shortest and most compact; and to procure these it eats into the body of the stuff, rejecting the pile or nap, which it necessarily cuts across at the origin, and permits to fall, leaving it threadbare, as if it had been much worn. It must have been this circumstance which induced Bonnet to fancy (as we have already mentioned) that it cuts the hairs to make itself a smooth, comfortable path to walk upon. It would be equally correct to say that an ox or a sheep dislikes walking amongst long grass, and therefore eats it down in order to clear the way.
[There is a little insect closely allied to these moths, which does a vast amount of harm to the bee-combs. This is the honeycomb-moth, of which there are in England two species, both belonging to the genus Galleria. This little creature is continually trying to make its way into the hives, and is as continually opposed by the bees, who instinctively know their enemy. If it once slips past the guards, the unfortunate bees are doomed to lose a considerable amount of their stored treasures, and have sometimes been so worried that they have been obliged to leave the hive altogether.
As soon as it can hide itself in an empty cell—an easy matter enough for so tiny a moth, which harmonizes exactly in colour with the bee-combs—it proceeds to lay its eggs, and, having discharged its office, dies. The eggs soon hatch into little grubs and caterpillars with very hard horny heads and soft bodies. As soon as they come into the dark world of the hive, they begin to eat their way through the combs, spinning the while a tunnel of silk, which entirely protects them from the stings of the bees. They can traverse these tunnels with tolerable speed, so that the bees do not know where to find their enemies; and if perchance they should discover one of them at the mouth of its burrow, the hard, horny head is all that is visible, and against its polished surface the sting of the bee is useless. The rapidity with which they drive the silken tubes through the comb is really marvellous; and even if they get among a collection of empty bee-combs, they make as much havoc as if they were bred in the hive from which the combs were taken.
In the accompanying illustration are seen figures of the two species of honey-moths, together with their tunnels. The species may be easily distinguished by the shape of the wings, Galleria alvearia having, as seen at Figs. b, c, the ends of its wings rounded, and Galleria cereana having them squared.
Some moths, also belonging to the vast Family Tineidæ, do much damage to grain, and have also the habit of spinning silken tissues as they eat their way through the grain. One of them is more plentiful on the Continent than in England, but is known in this country by the name of the mottled woollen moth (Tinea granella)].
The caterpillar, which is smooth and white, ties together with silk several grains of wheat, barley, rye, or oats, weaving a gallery between them, from which it projects its head while feeding; the grains, as Réaumur remarks, being prevented from rolling or slipping by the silk which unites them. He justly ridicules the absurd notion of its filing off the outer skin of the wheat by rubbing upon it with its body, the latter being the softer of the two, and he disproved, by experiment, Leeuwenhoeck’s assertion that it will also feed on woollen cloth. It is from the end of May till the beginning of July that the moths, which are of a silvery grey, spotted with brown, appear and lay their eggs in granaries.
Transformations of the Grain-moths.
a, Grain of barley, including a caterpillar;
b, c, the grain cut across, seen to be hollowed out,
and divided by a partition of silk;
d, the moth (Tinea Hordei);
e, grains of wheat tied together by the caterpillar;
f, g, the caterpillar and moth (Euplocamus granella).